Engineering Entrance Exam / Admission Application Forms 2017

Question 9.1:
A small candle, 2.5 cm in size is placed at 27 cm in front of a concave mirror of radius of curvature 36 cm. At what distance from the mirror should a screen be placed in order to obtain a sharp image? Describe the nature and size of the image.
If the candle is moved closer to the mirror, how would the screen have to be moved?Answer
Size of the candle, h = 2.5 cm
Image size = h’
Object distance, u = −27 cm
Radius of curvature of the concave mirror, R = −36 cm